Induction furnace



April 28, 1931. N. R. DAVIS ET AL 1,302,707

I INDUCTION FURNACE Filed May 7, 1950 INVENTORS A eVjL eR.Davis and P121717 GHBlirb ridge 7 AT'ToRNEY Patented Apr. 28, 1931 UNITED STATES PATENT OFFICE NEVILLE RYLAND DAVIS, OF SALE, AND PHILIP GEORGE BOULDER BURIBRIDGE, 0F

MANCHESTER, ENGLAND, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANU- FACTURING COMPANY, A CORPORATION OF PENNSYLVANIA INDUCTION FURNACE Application filed May 7, 1980, Serial No. 450,842, and in Great Britain May 8, 1929.

Our invention relates to .furnaces and more particularly to electric induction fur- DECGS.

An object of our invention is to provide a relatively simple and easily manipulated template for defining a melting chamber in an electric induction furnace.

Our invention relates particularly to electric induction furnaces of the kind in which a crucible or lining is made by ramming a suitable sand or some other suitable granular refractory material between a template and the energizin coil, the template being af erwards heate to sinter the sand or other refractory material.

In manufacturing furnaces having linings of the kind just mentioned, it has been found that the forces exerted on the energizing coil by reason of the expansion .of a tubular metal template and the sand, when heated, may strain the coil to an undesirably high degree, whereby it may fail ultimately because of either electrical or mechanical reasons.

In practicing our invention, which is designed to overcome the above mentioned diflicult'y, we provide a template within an external casing and an energizing coil located in granular refractory material within such casing, the template being made of relatively thin metal and of tubular shape in lateral section and provided with one or more inwardly folded portions which are readily deformable, so that they will yield when the template expands, as well as a slip being shown as substantially circular in sec ing 12 and includes a plurality of turns of an electric-conducting member, here shown as being substantially rectangular in lateral section and, while no terminals for the energizing coil are shown, it is to be understood that such are actually provided in a manner Well known in the art. In order to better protect the conductor, constituting the plurality of turns of the coil 13, from the relatively high temperature obtaining in an induction furnace when operating to melt metals or alloys, we provide a tubular mem ber 14 of solid electrical-insulating material, such as mica.

A template 16, which is shown as being substantially circular in lateral section, is located within the external casing 11 and the coil Band is of such radial dimensions as to permit of locating a relatively large amount of the refractory material 12 between its outer surface and the inner surface of the member 14 which is usually rammed into place. The template 16 may be provided with a bottom closure 17 which may be s 0t welded to the bottom edge of its tubu ar body portion at a relatively small number of places to permit the tubular wall to move slightly relatively thereto. 2

A cover 18 is made of a highly refractory molded material and may include a pouring spout 19 and cooperate with a plurality of annular layers 21 of molded refraction bricks to provide an adequate cover for the furnace. While we have shown a specific form of cover, we do not desire to be limited thereto as these details are shown for illustrative purposes only and constitute no part of our invention.

After the inner portion of the refractory lining 12 has been rammed into place between the casing 11 and the outer surface of the template 16, it is usually desired to sinter the inner portion of the refractory lining immediately adjacent to the melting chamber 22, and this is best effected by energizing the coil 13 to heat the template 16. It has been found that, if a substantially solid tubular template is provided, that is, a template the wall of which is unbroken, the template will expand to an undesired high degree and endanger not only that portion of the lining located between it and the energizing coil, but may also damage the energizing coil. Hence, we provide the template with one or more readily deformable portions, preferably by bending a portion or a plurality of portions of the thin metal inwardly, as is shown more particularly at 23 in Fig. 20f the drawings.

In order to prevent the initially loose refractory material from flowing into the recess in the template, we provide a slip-joint cover 24 which may be made of relatively thin metal of substantially the same length as the template and have one of its edges welded to the template at a few spots.

Referring to'Fig. 3 of the drawings, we have there illustrated a'substantially cylindrical template 26 which is provided with a plurality of inwardly projecting portions 27, each recess thus constituted being covered by an outer metal member 28 of substantially the same length as the template 26 and having one edge spot-welded to the outer surface of the template at a relatively few places. While the template 16 is illustrated as being discontinuous as to its peripheral continuity, we have shown the template 26 as having a substantially continuous sheet metal wall shaped to include the inwardly folded portions and then having its abutting edges spot-welded at a pluralityof places to hold the same in its original shape during the ramming operation.

Referring more particularly to Fig; 4 of the drawings, we have there illustrated a polygonal tubular template 31 having 'inwardly folded portions 32 at certain of the external angles and slip covers .33 of angle bar shape, to cover the outside of the recesses formed by the inwardly projectin portions, in order to prevent the entrance of sand into these recesses during the-early stages of manufacture of the furnace.

Referring more 'particularlyto Fig. 5 of the drawings, we have there illustrated a substantially circular template 36 having a readily deformable portion 37 of somewhat different and more intricate shape than the one shown in Figs. 2, 3 and 4. A cover 38 is provided for the portion 37, as hereinbefore set forth for the other templates.

It will be noted that, if one part of the periphery of the template be considered as substantially stationary, the other part thereof immediately adjacent thereto and separated therefrom by the inwardly projecting, readily deformable portions may move toward the other portion when the template is of this template, particularly so if metals or alloys other than that from which the template is made are to be melted in the furnace chamber. It is, therefore, necessary only to continue the energization of the coil 13 and possibly to add other raw material to be melted in the furnace chamber which will cause melting of the metal of the template 16 in due course, and it may thereafter be poured from the chamber 22, it being understood that suitable tilting means is provided in a manner well known in the art.

While we have illustrated a particular embodiment of furnace structure, we do not desire to claim this, as our invention is more particularly in the thin-wall metal template,

and various modifications may be made in-- the device embodying our invention without departing from the spirit and scope'thereof, and we desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the appended claims.

We claim as our invention:

1. A furnace including a casing havinga granular lining of refractory material, a tubular template located within, and in engagement with, the granular lining to effect sintering thereof when heated, readily deformable means embodied in said template to prevent the exertion of pressure against said lining when expansion is caused by heat.

2. A furnace including an exterior casing having an initially-granular lining of refractory material, a tubular template within the lining for defining a melting chamber therein, said template including a portion which is readily deformable and a sli -joint cover therefor to preclude the temp ate from so expanding, whenheated, as to exert radial pressure against the lining.

3. An induction'furnace including an external casing having an initially-granular lining of refractory material and an energizing coil embedded in the lining, atubular lining of refractory material and an energizing coil embedded in the lining, a tubular temp ate of relatively thin metal within the refractory lining for defining a; melting. chamber therein, said template having an inwardly-folded andreadily deformable portion to preclude excessive radial expansion of the template when heated by inductive effect from the energizing coil to effect sintering of the inner portion of the lining adjacent to the melting chamber, and a cover for said inwardly-folded portion secured to the template.

5. An induction furnace including an external casin having an initially-granular lining of re ractory material and an energizing coil in the lining, a tubular template of relatively thin metal and of polygonal shape in lateral section located within the lining for defining a melting chamber therein, said template having inwardly-projecting and readily-deformable portions at certain of the respective angles of the template to preclude excessive expansion of the template when heated inductively by the energizing coil to effect sintering of the inner portion of the lining adjacent to the melting chamber, and covers for said respective inwardlyfolded portions having one edge of each secured to the template.

In testimony whereof, we have hereunto subscribed our names this twent -third dayof April, 1930, and this twenty-t 'rd day of April, 1930.

NEVILLE RYLAND DAVIS.

PHILIP GEORGE BOULDER BURBRIDGE. 

